Question

When a solid is placed in a container and heat is applied, a phase change occurs. Watch the video and identify which of the following statements are correct. Check all that apply. View Available Hint(s) Check all that apply. The temperature increases while all of a liquid is converted to a gas. The average kinetic energy of the system changes while all of a solid is converted to a liquid. Temperature remains constant while all of a solid is converted to a liquid. When heat is applied to a solid, the molecular motion decreases as the temperature increases. When a solid is converted to a liquid, heat is absorbed.

Answer 1

The temperature remains constant during the phase change from solid to liquid and from liquid to gas, as the heat added is used to break intermolecular bonds. Heat is absorbed during melting and vaporization, which are endothermic processes. Molecular motion increases with heat, not decreases.

Step-by-step explanation:

When a solid is placed in a container and heat is applied, various changes occur during the transition to a liquid and then to a gas. Firstly, the temperature increases as the solid absorbs heat, causing an increase in the vibrational motions of the molecules; however, during the phase change from solid to liquid, the temperature remains constant. This is because the energy being added is used to break the intermolecular bonds rather than increasing the kinetic energy of the particles. Once all of the solid has been converted to a liquid, the temperature can rise again as additional heat is added. Similarly, when a liquid becomes a gas, the temperature remains constant as heat is absorbed to overcome the attractive forces between the liquid particles.

Heat is absorbed during the process of melting a solid into a liquid, and the temperature of the substance does not change during the phase change. This concept is called an isothermal process. Conversely, during freezing and condensation, heat is released. When a solid turns into a liquid, this process is endothermic, and similarly when a liquid transitions to a gas, additional energy is needed to make this phase change occur.

The correct statements from the options provided would be that the temperature remains constant while all of a solid is converted to a liquid, and that heat is absorbed when a solid is converted to a liquid. It is incorrect to say that the temperature increases while all of a liquid is converted to a gas or that the average kinetic energy changes while all of a solid is converted to a liquid, as phase changes occur at a constant temperature. Additionally, it is incorrect that molecular motion decreases when a solid is heated; instead, molecular motion increases.

Answer 2

Step-by-step explanation:

Phase change is said to occur when a substance from one state of matter changes to another state. Phase change occurs at a fixed temperature. For example, water boils and converts to steam at 100°C. During the phase change, the average kinetic energy of the system remains constant which is indicated by constant temperature. Actually, the molecular motion does increase with increase in heat but heat is absorbed in breaking the bonds and formation of new bonds.

Thus, third and last statement are correct.